1. Field of the Invention
The present invention relates to a semiconductor substrate including a so-called SOI (silicon on insulator) structure in which a semiconductor layer is provided over an insulating surface, semiconductor device, and a manufacturing method thereof.
2. Description of the Related Art
An integrated circuit which uses a semiconductor substrate called a silicon-on-insulator (hereinafter, also referred to as an SOI) that has a thin single crystal semiconductor layer provided on an insulating surface has been developed, instead of an integrated circuit which uses a silicon wafer manufactured by thinly slicing an ingot of a single crystal semiconductor. The integrated circuit using an SOI substrate has been attracting attention as an integrated circuit which reduces parasitic capacitance between a drain of the transistor and the substrate and improves the performance of a semiconductor integrated circuit.
There are various manufacturing methods of an SOI substrate, but an SOI substrate formed by a method called Smart-Cut™ is known as an SOI substrate with both quality of an SOI layer and easiness in production (throughput). This SOI substrate is formed in the following manner; hydrogen ions are implanted to a bond wafer formed of a silicon layer, and the bond wafer is bonded to another wafer (base wafer) at room temperature. Here, a strong bond can be formed by van der Waals' forces at room temperature. As a result, the bond wafer bonded with the base wafer is separated using a layer, in which hydrogen ions are implanted, as a boundary by heat treatment at a temperature of about 500° C.
Further, a method of forming a single crystal silicon thin film over a crystallized glass which is high heat resistant glass by utilizing Smart Cut (registered trademark) is known (see Patent Document 1: Japanese Published Patent Application No. H11-163363).